Mine roof bolt installation



P 1960 J. B. DEMPSEY 2,952,129

MINE. ROOF sour INSTALLATION Filed Jan. 9, 1958 INVENTOR JO SEPH B.DEMPSEY PM. 1. BYWWQW ATTORNEYS United States Patent MINE RooF BOLTINSTALLATION Joseph B. Dempsey, 910 Colgate Road, Marietta, Ohio 8 FiledJan. 9, 195a, Ser. No. 707,988

6 Claims. or. 61-45) 'This invention relates to mine roof boltinstallations and more particularly to improvements in suchinstallations for eifectively retaining a grouting material thereinprior to its hardening. This application constitutes acontinuation-in-part of my copending application Serial No. 398,826,filed December 17, 1953, issued April 8, 1958, as Patent No. 2,829,502.

Mine roof bolts, and their usages, are known in the art and' usuallycomprise a headed bolt of from about three to about five feet long andan expansible anchoring means threadedly engaged therewith. In use, amine roof bolt'is inserted in a drilled hole in a mine roof, with theanchoring means at the inner end of the hole and a lafgewasher seatedagainst the head of the bolt and abutting against the ceiling of themine. Thereupon, the anchoring means is actuated to expand into tightgripping engagement with the side walls of the hole, and the boltis'placed under tension between the washer and the anchoring means. Theinstallation of mine roof bolts in this manner in a plurality of holesin a mine roof serves to lock the "roof strata together to preventfalling. Thus, mineroof bolts eliminate the timber shoring previouslyused to support the roofs of passageways and rooms in a mine. I l

r :In some instances, however, mine roof strata is somewhat soft and onexposure to air eventually will slough oiflcrumble, or spall, thuspermitting a mine roof bolt to fallout of the hole by failure of theformation about the bolt anchoring means. In this type of roof strata,mine roof bolts heretofore have provided only a temporary support forthe roof, the effectiveness of which decreased withpassage' of time.Accordingly, in the aforedescribed type of mine roof formation, mineroof bolt installations which are not cemented in or grouted can be usedonly where the passageway or room is not a permanent part of the minelabyrinth. Even so, however, the installation washer of the typedisclosed in the aforesaid application satisfactory for mostinstallations, leakage of the grouting material past the washer is notpositively prevented,

particularly in installations where the wall of the hole is relativelyunstable.

Accordingly, it is an object to the present invention to provide a mineroof bolt installation having improved means for retaining a groutingmaterial therein prior to its hardening which overcomes thedisadvantages noted above.

Another object of the present invention is the provision of a groutingmaterial retaining means of the type described which is activated intopositive sealing engagement with the wall of the mine roof hole inresponse to the expansion of the anchoring means of the mine roof boltassembly. 1

Still another object of the present invention is the provision of a mineroof bolt assembly having improved means for sealing the mine roof holeto retain grouting material therein prior to its hardening, which meansis simple but effective in operation and economical to manufacture.

These and other objects of the present invention will become moreapparent during the course of the following detailed description andappended claims. 1

The invention may best be understood with reference to the accompanyingdrawings wherein an illustrative em-' bodiment is shown.

In the drawings: 7

Figure 1 is a vertical sectional view of a mine r'oof hole showingtherein, in elevation, an installation embody ing the principles of thepresent invention;

Figure 2 is a fragmentary cross-sectional view taken along the line 2-2of Figure 1 showing the sealing means in compressed engagement with theurine roof hole; H

Figure 3 is a cross-sectional view taken along the line 33 of Figure l;

Figure 4 is an elevational view, partly in section of the resincontainer; and t Figure 5 is an elevational View, partly in sectionofthe catalyst container.

Referring now to Figure 1 of the drawings, there is shown therein a hole10 which has been drilled upwardly from the ceiling 12 of a mine room orpassageway into the roof strata 14 thereabove. Positioned in the hole 10is a mine roof bolt assembly including a bolt,16 and an able in stratawhich tends to eventually crumble or spall because of exposure to air.Because of its weight, a falling mine roof bolt can be quite dangerousto human life; Additionally, the gradual lessening of the supportingeffectiveness of a mine roof bolt tends to create a somewhat dangeroussituation.

-In the aforesaid copending application, there is disclosed a grouted orcemented mine roof bolt installation which includes a capsule,containing a suitable grouting material, insertable into the'mine roofhole together with and ahead of the mine roof bolt assembly. Afterinsertion of the bolt assembly and capsule is completed, the latter isopened, as by rupture against the end of the mine roof hole, and thegrouting material therein is allowed to How by gravity within the spacein the hole occupied by the bolt assembly. The bolt of the assembly hasa washer mounted thereon below the expansible anchoring means on theupper end thereof, which washer engages the wall of the hole so as toconfine the grouting material within the spacein the hole adjacent theanchoring means iiiitfl' hardened While a simple flexible disk-shapedanchoring means 18 of a type disclosed in Dempsey Patent No. 2,753,750issued July 10, 1956, and to which reference is made for a more detaileddescription of the anchoring means. The anchoring means 18, whichnormally is cylindrical and of a diameter slightly less than that of thehole 10, includes a two-part expansible anchor" iililg shell 20 and awedge-shaped nut 22 for expandingthe s ell.

The shell 20, which normally is generally circular in transverse sectionand of a diameter only slightly less than that of the drilled hole 10,has two diametrically. opposed parts 24, each part being formed as alongitudinal-tapering segment of a cylinder. The tapering longitudinalplane edges 26 of each part 24 are disposed in a common plane with theedge planes of both parts being upwardly divergent. The smaller andupper ends of the two parts 24 forming the shell 20 are connectedtogether by a spring-steel band-like connecting member 28 that issubstantially U-shaped. The connecting member 28 has legs 30 whichnormally are generally parallel and extend generally longitudinally ofthe shell 20 and a base 32 which extends transversely of the shellsomewhat above the upper ends of the two shell parts 24.' The twolegs 30of the connecting member 28 may be securedto. the

, shell parts 24 in any appropriate manner, but, as shown,

fit into recesses 34 therein and are connected thereto by Patented Se t.13, 1960,;

of the shell parts 24 preferably are provided with a plu-- rality ofstep-like circumferential serrations 38 and vertical serrations(not'shown) for embedding and gripping grip upon the side walls of thehole and permit the entire roof bolt assemblyto fall out ofthe same.

In order to obviate the foregoing difiiculty, an installa tion inaccordance with this invention seals oif the strata engagement with theside walls of the hole 10, 'as later explained. Preferably, the'bottomedge 40 of each shell part 24 is sharp, for a reason that will becomeapparent later.

The nut 22 is disposed between the two parts 24 of the shell 20 and hasopposite plane wedging surfaces 42 complementary to, and inmutually-wedging engagement with, each pair of opposed side plane edges26 of the shell parts. Preferably, the wedging surfaces 42 onthe nut 22are longer than the longitudinal side 'edges- 26 ofthe shell parts 24and extend above, the two shell parts, so that when the shell 20 isexpanded by downward movement of the nut 22 relative thereto, as laterexplained, the entire length of the wedging surfaces or plane edges 26of the two shell par-ts'is engaged with the wedging surfaces on the nutThe exterior surfaces of the nut 22, between its wedging surfaces 42,are arcue ate in transverse section to correspond to the circularperipheral outline of the shell 20. At its larger end, the nut 22 isprovided with diametric longitudinal channels or grooves 44 toaccommodate the legs 30' of the connecting member 28*.

The shank 46 of the bolt 16 is threaded into the nut 212, from the lowerend thereof, and the lower or outer end of the bolt has an enlarged head48 having a washer supporting flange 50 of greater diameter than thediam- I eter of the shell and nut assembly or anchoring means 18 whenthe latter is unexpanded, and a non-circular wrench-engageable portion52. Seated on the flange 50 of the bolt head 48 is a large washer 54 forengagement with the ceiling 12 about the hole 10. The inner diam eter ofthe washer 54 preferably is slightly larger than the diameter of theanchoring means 18 whenthe latter is unexpanded, so that the washer canpass thereover 7 into engagement with the flange 50 on the bolt head 48without disassembly of the bolt 16 from the nut 22.

In use, the mine roof bolt assembly, with the washer 54 in placethereon, is inserted upwardly into the drilled hole until the washerengages the ceiling 12. In so doing, the upper end of the nut 22 willabut against the underside of the base 32 of the member 28, connectingthe shell parts 24, to carry the latter along with the bolt and nut asthe assembly is pushed upwardly into the hole 10. Prior to suchinsertion, the two shell parts 24 are sprung somewhat apart, so that asthe assembly is pushed upwardly into the hole 10, the sharp bottom edges40 of the shell parts drag against and engage the sides of the hole andretain the assembly therewithin after inser tion thereinto. After theassembly has been thus inserted to its full length, the bolt 16 ispulled down somewhat, to thus force the wedging surfaces 42 of the nut22 into expanding wedging engagement with the shell parts 24 to forcethe latter oppositely apart into gripping engagement with the side wallsof the hole 10. The bolt 16 is then rotated, as by an appropriate powertool (not shown) applied to the non-circular portion 52 of the bolt head48, to thereby draw the washer 54 upwardly, into engagement with theceiling 12 and thereafter draw the nut 22 downwardly into greaterwedging engagement with the two shell parts 24 and force the latter inopposite directions into firmer gripping engagement with the side wallsof the hole. 1

V The foregoing steps are the conventional method of installing a mineroof bolt of the type shown in the aforementioned patent. It willreadily be seen, however, that the side walls of the hole 10 about theanchoring means 18 are exposed to air, and in the event that the roofstrata 14 is of thetype that will eventually crumble or spall upon suchair exposure, such crumbling or spalling about the anchoring means willeventually relieve its 14 engaged by and immediately above and below theanchoringmeaus 18 fiorn access to air. An installation embodying thisinvention also excludes air from the hole once the assembly is installedtherein. Hence, a mine roof bolt installation embodying this inventionis sub- 4 stantially permanent.

In order to provide a substantially permanent installa-' tion, aflowable plastic or liquid settable or hardenable cementitious materialis applied and confined around and strata frequently is damp. Materialssuitable for this purpose may include cement grout, a Water-insolubleglue,

1 and syntheticresins. Synthetic resins which are activated by theaddition of a suitable catalyst are particularly suited to the presentpurposebecause of the ease with which they can be handled.

For example, there can be used as the grouting material the product madeby mixing a spray-dried melamineformaldehyde condensation product, e.g.,as made in example l of Widmer Patent No. 2,318,121 with an aqueoussolution of an acid catalyst such as oxalic acid or ammonium sulfate.Thus, parts of the resin can be mixed with a solution of 1' part ofoxalic'acid in 60 parts of water or 5 parts of ammonium sulfate in 45parts of water. I

An alternative grouting material can be prepared by mixing an epoxyresin such as those shown in Bradley Patent 2,500,600 with an aminecuring agent. In a specific example 100 parts of Epon 828 (a liquidbisphenol A-epichlorhydrin resin) and 10 parts of diethylene tnamine asa curing agent were mixed to form the grouting compositions.

, Other resins which can be employed are phenol-formaldehyde,phenol-furfural, furfuryl alcohol, urea-formaldehyde and polyesterresins, e.g., polyethylene 'maleateadipate modified with styrene.

A preferred arrangement for handling such resins is shown in Figures 1,4 and 5. The resin itself is placed in a first container or capsule 56,shown in Figure 4, which container has suificient capacity to hold thedesired quantity of resin and to receive the catalyst so that the lattercan be mixed therewith prior to insertion within the mine roof hole. Thecatalyst can be separately retained in the container 56, as by arupturable capsule or compartment disposed therein, however, as shown inFigure 5, the catalyst is contained Within a separate container 58.

- Prior to installation, the containers 56 and 58 are sealed by suitableclosures 60 and 62, respectively. When it is desired to utilize theinstallation, the closures 60 and 62 are removed and the catalyst in thecontainer 58 is poured in with the resin in the container 56 and stirredor otherwise thoroughly mixed therewith as, for example, by replacingthe closure 60 and shaking, provided the mixture is sufii'cientlyviscous to permit such action. The container 56 with the mixture thereinis then inserted in the hole 10 and movedupwardly therein by theinsertion of the mine roof bolt assembly therein, in its normal way. Theclosure 60 may be replaced on the container 56 prior to its insertion inthe hole, although this is notnecessary, and therefore, in order to savetime, it is preferable to insert the container in the hole with itsupper end open is preferably made of a rupturable or fracturablematerial such as glass, plastic or the like;

The present; invention is more particularly concerned with a novelsealing means, generally indicated at 64, which is operable to engagethe wall of the hole adjacent and below the expansible shell 20 toretain the resin mixture in the hole thereabove in surrounding relationto the nut 22 and expansible shell. The sealing means 64 comprises arigid disk or washer 66 which is slidably mounted on the upper end ofthe bolt 16 and secured thereon against downward movement beyond aposition spaced just below the shell 20 by projections 68 or the likeformed on the bolt by interrupting the exterior surface thereof with apress or the like. Mounted on the bolt above the washer 66 is a gasketor flexible washer 70 which is preferably made of foamed natural rubber,synthetic rubber or plastic. Preferably, the gasket 70 is made of aclosed cell sponge construction so that in its normal condition it willeffectively prevent the passage of a fairly thick liquid. The gasket isalso desirably of a relatively great thickness, as, for example, threequarters of an inch, so as to provide adequate radial movement uponcompression. If desired,

an upper rigid disk or washer 72 is slidably mounted on the bolt abovethe gasket or flexible washer 70.

Operation As indicated above, the open container 56 having the mixedresin and catalyst therein is inserted into the hole ahead of and by theinsertion of the roof bolt assembly therein, as shown in Figure 1. Inmost installations, this insertion is performed by the power tool usedto turn the bolt head to expand the anchoring assembly. The hole 10 hasbeen previously drilled to a predetermined height in the mine roof sothat the strata defining the upper end thereof will be engaged by thecontainer during the upward inserting movement, and thus fractured justprior to or simultaneously with the assembly reaching its fully insertedposition within the hole.

When the assembly is fully inserted, the operator actuates the powertool to turn the bolt head and effect expansion of the anchoringassembly. During this expansion it will be noted that the nut 22 movesdownwardly on the bolt 16. The flexible washer 70 is retained on thebolt against downward movement by the lower rigid washer 66 in aposition to be engaged by the lower end of the nut 22 during itsdownward movement. Where the upper rigid washer 72 is not utilized, theflexible washer 70 is directly engaged by the lower end of the nut andthus expanded into sealing engagement with the adjacent strata 14defining the hole and the adjacent exterior of the bolt. Where the upperrigid washer 72 is utilized, the lower end of the nut engages the samewhich in turn serves to evenly compress the flexible washer radiallyinto sealing engagement with the adjacent hole defining strata andexterior bolt surface, as shown in Figure 2.

The compressed engagement of the flexible washer 70 thus caused by theexpansion of the anchoring means of the roof bolt assembly serves topositively seal the grouting material flowing by gravity from the openedor fractured container into the space in the hole 10 thereabove andhence around the shell 20 and nut 22. The expansion of the anchoringmeans and the compression of the gasket or flexible washer in responsethereto is readily accomplished before the grouting material has time toreach the gasket during its flow from the fractured container.

It will thus be seen that the objects of this invention have been fullyand effectively accomplished. It will be realized, however, that variouschanges may be made in the specific method and apparatus shown anddescribed for the purpose of illustrating the principles of thisinvention without departure from such principles. Accordingly, thisinvention includes all modifications of apparatus and method encompassedwithin the spirit and scope of the following claims.

I claim:

1. A mine roof bolt assembly comprising an elongated bolt, expansibleanchoring means on one end of said bolt insertable therewith upwardlyinto a mine roof hole, said anchoring means including portions movablelongitudinally with respect to said bolt for efiecting expansion of saidanchoring means, and radially expansible sealing means disposed adjacentsaid anchoring means and engageably associated with said anchoring meansfor radial expansion into engagement with the hole at a position abovethe lower end thereof in response to at least a portion of the relativelongitudinal movement between said bolt and anchoring means portions toeffect expansion of said anchoring means.

2. A mine roof bolt assembly comprising an elongated bolt having a wedgemember threaded on one end thereof, expansible anchoring shell means onsaid wedge member operable to expand in response to longitudinalmovement of said wedge member with respect thereto as a result ofturning said bolt, and radially expansible sealing means carried by saidbolt in a position to be engaged by said wedge member during itslongitudinal movement with respect to said anchoring shell means tothereby radially expand said sealing means.

3. A mine roof bolt assembly as defined in claim 2 wherein said sealingmeans comprises an annular washer of resilient material.

4. A mine roof bolt assembly as defined in claim 3 wherein said washerresilient material is foamed.

5. A mine roof bolt assembly as defined in claim 3 wherein said sealingmeans further includes a rigid disk disposed in engagement with thesurface of said washer remote from said anchoring means, and meansmounting said disk on said bolt against longitudinal movement in adirection away from said anchoring means.

6. A mine roof bolt assembly as defined in claim 5 wherein said mountingmeans comp-rises ears formed in said bolt engaging said disk.

References Cited in the file of this patent UNITED STATES PATENTS2,570,003 Palmer Oct. 2, 1951 2,704,680 Bedford Mar. 22, 1955' 2,829,502Dempsey Apr. 8, 1958 2,850,937 Ralston Sept. 9, 1958

